1. Field of the Invention
The present invention generally relates to method of and apparatus for transmitting digital data, and more particularly, is directed to improvements in a digital data transmitting method by which 8-bit word sequence data including word synchronous data are produced for representing various image information such as information of digital luminance and chrominance signals constituting a digital video signal and converted into serial digital data to be transmitted through a data transmission line and in a digital data transmitting apparatus used for putting the above-mentioned method into practice.
2. Description of the Prior Art
In the field of data transmission in which digital data containing information data representing various signal information are transmitted, an electric transmission system and an optical transmission system have been proposed to be put into practice. In the case of the electric transmission system, the digital data are converted into one or more electric signals to be transmitted through one or more transmission lines each made of a coaxial cable or a pair of twisted lines. In the case of the optical transmission system, the digital data are converted into one or more optical signals to be transmitted through one or more transmission lines each made of an optical fiber cables. The formats of the digital data are classified broadly into two categories, one of which is an STM (Synchronous Transfer Mode) format in which a constant frame period is set and the other of which is an ATM (Asynchronous Transfer Mode) format in which a constant frame period is not set.
The current digital networks, in which the digital data transmission systems as mentioned above have been adopted, have developed on the basis of telephone line networks. Data multiplexing for actualizing highly efficient data transmission and broad-band signal transmission at high speed based on data to be transmitted are inevitably required to the information transmission through the digital networks with the developments thereof. Accordingly, the technology called SDH (Synchronous Digital Hierarchy) been established by the ITU-T (former CCIR) the technology called SDH (Synchronous Digital Hierarchy) as one of systems for multiplexing data to be converted into high speed and broad-band signals and transmitting the high speed and broad-band signals thus obtained.
The SDH has proposed a new STM format with synchronous multiplexing structure including a basic unit called STM-1, which is fit for high speed and broad-band signal transmission services in future. The STM-1 is a transmission signal with a period composed of 9 rows, each of which is composed of a data section of 270 bytes (1 byte=8 bits), that is, 270 bytesxc3x979=2,430 bytes, as shown in FIG. 1. This unit periodic segment of 2,430 bytes is called a frame. The first 9 bytes in 270 bytes contained in each of the 9 rows constituting each frame form a portion of a section overhead (SOH) and AU pointer. The rest 261 bytes in 270 bytes contained in each of the 9 rows form an information data area.
The portion of the section overhead and AU pointer is composed of 9 bytexc3x979=81 bytes including A1, A2, B1, B2, C1, D1xcx9cD12, E1, E2, F1, K1, K2, H1, H2, H3, Z1 and Z2 each representing 1 byte. These bytes have their respective contents as shown in FIG. 1. Each of A1 and A2 (frame pattern) is an 8-bit word synchronous data and three successive A1s at the beginning portion of the first row and three successive A2s following the three successive A1s in the first row form a synchronous pattern in each frame. The A1 which is the 8-bit word synchronous data is allotted a specific code of 11110110 and the A2 which is also the 8-bit word synchronous data is allotted another specific code of 00101000.
The period of the STM-1 is determined to be, for example, 125 xcexcs. Consequently, the transmission capacity of the STM-1 is calculated to be 270 bytesxc3x979xc3x97{fraction (1/125)}xc3x9710xe2x88x926secondsxc3x978=155.520 Mbit/s (155.520 Mbps).
There has been further proposed a high speed data transmission in which of transmission signals each functioning as the STM-1 are multiplexed. The transmission signal thus obtained by multiplexing is called STM-N. The STM-N is formed, for example, by multiplexing transmission signals STM-1 #1, STM-1 #2, . . . , STM-1 #n, each functioning as the STM-1, in the manner of byte-intreleaving at a data multiplexing portion MP, as shown in FIG. 2.
The high speed data transmission service called SONET (Synchronous Optical Network) in the United States of America has been generally known as a communication service to which the SDH as aforementioned is practically applied.
In the field of video signals, digitalization of video signals has been aimed for actualizing diversification in information transmission, improvements in quality of reproduced images based on video signals and so on. For example, there has been proposed the High Definition Television (HDTV) system which uses a digital video signal representing video signal information. The digital video signal under the HDTV system (hereinafter, referred to an HD digital video signal) is formed, for example, in accordance with such data formats as shown in FIGS. 3A and 3B.
The data formats shown in FIGS. 3A and 3B include a luminance signal data sequence (Y data sequence) as shown in FIG. 3A, which represents a luminance signal component of a video signal, and a color difference signal data sequence (PB/PR data sequence) as shown in FIG. 3B, which represents color difference signal components of the video signal. Each of data words constituting the Y data sequence or the PB/PR data sequence is composed of 10 bits. Namely, each of the Y data sequence and the PB/PR data sequence is formed into 10-bit word sequence data. A part of the Y data sequence which includes a portion corresponding to a horizontal blanking period and parts of portions corresponding to a couple of video data periods appearing before and after the horizontal blanking period in a horizontal period of the Y data sequence is shown in FIG. 3A. Similarly, a part of the PB/PR data sequence which includes a portion corresponding to a horizontal blanking period and parts of portions corresponding to a couple of video data periods appearing before and after the horizontal blanking period in a horizontal period of the PB/PR data sequence is shown in FIG. 3B.
In the Y data sequence, time reference code data SAV (Start of Active Video) which are composed of four 10-bit words (3FF(Y), 000(Y), 000(Y), XYZ(Y): 3FF and 000 are hexadecimal numbers and (Y) indicates a word contained in the Y data sequence) are provided just before a portion corresponding to the video data period and another time reference code data EAV (End of Active Video) which are composed of four 10-bit words (3FF(Y), 000(Y), 000(Y), XYZ(Y)) are provided just after the portion corresponding to the video data period. Similarly, in the PB/PR data sequence, time reference code data SAV which are composed of four 10-bit words (3FF(C), 000(C), 000(C), XYZ(C): 3FF and 000 are hexadecimal numbers and (C) indicates a word contained in the PB/PR data sequence) are provided just before a portion corresponding to the video data period and another time reference code data EAV which are composed of four 10-bit words (3FF(C), 000(C), 000(C), XYZ(C)) are provided just after the portion corresponding to the video data period. The time reference code data EAV and SAV contained in the Y data sequence are provided in a portion corresponding to the horizontal blanking period of the Y data sequence and the time reference code data EAV and SAV contained in the PB/PR data sequence are provided in a portion corresponding to the horizontal blanking period of the PB/PR data sequence.
When the Y data sequence and the PB/PR data sequence are transmitted, the Y data sequence and the PB/PR data sequence are subjected to word multiplexing treatment under a condition in which the portion corresponding to the horizontal blanking period of the Y data sequence in which the time reference code data EAV and SAV are contained is synchronized with the portion corresponding to the horizontal blanking period of the PB/PR data sequence in which the time reference code data EAV and SAV are contained, so as to produce word multiplex data sequence formed into 10-bit word sequence data, as shown in FIG. 4, and the digital video signal in the form of 10-bit word sequence data formed in accordance with the data format of the word multiplex data sequence shown in FIG. 4 is converted into serial data to be transmitted.
In the word multiplex data sequence, multiplex time reference code data (multiplex SAV) which are composed of eight 10-bit words (3FF(C), 3FF(Y), 000(C), 000(Y), 000(C), 000(Y), XYZ(C), XYZ(Y)) are provided just before a portion corresponding to the video data period and another multiplex time reference code data (multiplex EAV) which are composed of eight 10-bit words (3FF(C), 3FF(Y), 000(C), 000(Y), 000(C), 000(Y), XYZ(C), XYZ(Y)) are provided just after the portion corresponding to the video data period.
Under such a situation, in order to make it possible to utilize effectively existing integrated circuit devices previously developed for the SDH on the occasion of construction of data transmitting and receiving circuits for digital video signals, it is strongly desired that the digital video signal formed in accordance with the data format of the word multiplex data sequence based on the Y data sequence and the PB/PR data sequence as described above is subjected to such data transmission that 8-bit word sequence data to which word synchronous data each allotted a predetermined specific code, such as A1 and A2 as aforementioned, are added, are produced based on the original digital video signal which is to be transmitted in a transmission side, and the 8-bit word sequence data thus produced are transmitted through a data transmission line.
Although, for the present, the digital video signal formed in accordance with the data format of the word multiplex data sequence based on the Y data sequence and the PB/PR data sequence is transmitted in the form of serial data at the bit transmission rate of 1.485 Gbps, it is presumable that in the near future a digital video signal formed in accordance with such a data format as the word multiplex data sequence is transmitted in the form of serial data at the bit transmission rate which is, for example, twice the previous bit transmission rate, namely, 1.485 Gbpsxc3x972=2.97 Gbps.
Considering that it is presumable that in the near future the digital video signal is transmitted in the form of serial data at the bit transmission rate which is selected to be extremely high under a condition in which it is strongly desired that the digital video signal formed in accordance with the data format of the word multiplex data sequence is transmitted in such a manner that the 8-bit word sequence data to which the word synchronous data each allotted the predetermined specific code are added, are produced based on the digital video signal which is to be transmitted in the transmission side, and the 8-bit word sequence data thus produced are transmitted through the data transmission line, if it is possible to transmit not only digital data formed into a single channel for representing a digital video signal but also multiplex digital data formed with digital data divided into a plurality of channels for representing a digital video signal, the data transmitting and receiving circuits used for the transmission of the digital video signal can be constructed with effective utilization of the existing integrated circuit devices previously developed and the digital video signal is utilized more effectively and the field of utilization of the digital video signal is desirably extended. The effective utilization of the digital video signal or the extension of the field of utilization of the digital video signal brings about further progress of technology in the field of electronic apparatus for professional use and home use.
However, any practical embodiment of digital data transmission system which can transmit multiplex digital data formed with digital data divided into a plurality of channels for representing a digital video signal in such a manner that 8-bit word sequence data to which word synchronous data each allotted a predetermined specific code are added, are produced based on the digital video signal which are to be transmitted, and the 8-bit word sequence data thus produced are transmitted through a data transmission line, has not been previously found.
Further, any literature or thesis disclosing the digital data transmission system which can transmit the multiplex digital data formed with the digital data divided into a plurality of channels for representing the digital video signal in the manner mentioned above, has not been previously found also.
Accordingly, it is an object of the present invention to provide a method of transmitting digital data, by which 8-bit word sequence data including word synchronous data are produced for representing various image information and converted into serial digital data to be transmitted through a data transmission line, and which avoids the aforementioned disadvantages encountered with the prior art.
It is another object of the present invention to provide a method of transmitting digital data, by which 8-bit word sequence data including word synchronous data are produced for representing various image information and converted into serial digital data to be transmitted through a data transmission line, and which can transmit multiplex digital data formed with digital data divided into a plurality of channels for representing a digital video signal in such a manner that 8-bit word sequence data to which word synchronous data each allotted a predetermined specific code, such as A1 and A2 as aforementioned, are added, are produced based on the digital video signal which are to be transmitted, and the 8-bit word sequence data thus produced are transmitted through the data transmission line.
It is a further object of the present invention to provide a method of transmitting digital data, by which 8-bit word sequence data including word synchronous data are produced for representing various image information and converted into serial digital data to be transmitted through a data transmission line, and which can transmit multiplex digital data formed with digital data divided into a plurality of channels for representing a digital video signal in such a manner that 8-bit word sequence data to which word synchronous data each allotted a predetermined specific code, such as A1 and A2 as aforementioned, are added, are produced based on the digital video signal which are to be transmitted, and the 8-bit word sequence data thus produced are transmitted through the data transmission line with transmission means which can be constructed with effective utilization of existing integrated circuit devices previously developed.
It is a further object of the present invention to provide an apparatus for transmitting digital data, by which 8-bit word sequence data including word synchronous data are produced for representing various image information and converted into serial digital data to be transmitted through a data transmission line, and which avoids the aforementioned disadvantages encountered with the prior art.
It is a further object of the present invention to provide an apparatus for transmitting digital data, by which 8-bit word sequence data including word synchronous data are produced for representing various image information and converted into serial digital data to be transmitted through a data transmission line, and which can transmit multiplex digital data formed with digital data divided into a plurality of channels for representing a digital video signal in such a manner that 8-bit word sequence data to which word synchronous data each allotted a predetermined specific code, such as A1 and A2 as aforementioned, are added, are produced based on the digital video signal which are to be transmitted, and the 8-bit word sequence data thus produced are transmitted through the data transmission line.
It is a still further object of the present invention to provide an apparatus for transmitting digital data, by which 8-bit word sequence data including word synchronous data are produced for representing various image information and converted into serial digital data to be transmitted through a data transmission line, and which can transmit multiplex digital data formed with digital data divided into a plurality of channels for representing a digital video signal in such a manner that 8-bit word sequence data to which word synchronous data each allotted a predetermined specific code, such as A1 and A2 as aforementioned, are added, are produced based on the digital video signal which are to be transmitted, and the 8-bit word sequence data thus produced are transmitted through the data transmission line with transmission means which can be constructed with effective utilization of existing integrated circuit devices previously developed.
According to a first aspect of the present invention, there is provided a method of transmitting digital data, which comprises the steps of obtaining first and second 8-bit word sequence data based on first and second digital image information data, respectively, causing each of the first and second 8-bit word sequence data to be subjected to 8 bits to 10 bits conversion (8B/10B conversion) to produce first and second 10-bit word sequence data, obtaining third and fourth 8-bit word sequence data based on the first and second 10-bit word sequence data, respectively, inserting an additional word data group including 8-bit word synchronous data allotted a predetermined specific code into each of the third and fourth 8-bit word sequence data at predetermined word intervals to produce first and second composite 8-bit word sequence data, converting the first and second composite 8-bit word sequence data into first and second serial data, respectively, and transmitting the first and second serial data through first and second transmission lines.
In one embodiment of the first aspect of the present invention, the first and second digital image information data are respectively digital data representing luminance signal information (luminance signal information data) and digital data representing chrominance signal information (chrominance signal information data) which constitute a digital video signal. In another embodiment of the first aspect of the present invention, the first digital image information data are two of data representing first, second and third primary color signal information which constitute a digital video signal and the second digital image information data are the rest of the data representing first, second and third primary color signal information.
According to a second aspect of the present invention, there is provided a method of transmitting digital data, which comprises the steps of causing luminance signal information data and chrominance signal information data which constitute a digital video signal to be subjected to bit-dividing to produce first and second divided bit word sequence data, causing each of the first and second divided bit word sequence data or each of the first divided bit word sequence data and compound bit word sequence data obtained by adding predetermined bit word data to the second divided bit word sequence data to be subjected to 8B/10B conversion to produce first and second 10-bit word sequence data, obtaining first and second 8-bit word sequence data based on the first and second 10-bit word sequence data, respectively, inserting an additional word data group including 8-bit word synchronous data allotted a predetermined specific code into each of the first and second 8-bit word sequence data at predetermined word intervals to produce first and second composite 8-bit word sequence data, converting the first and second composite 8-bit word sequence data into first and second serial data, respectively, and transmitting the first and second serial data through first and second transmission lines.
According to a third aspect of the present invention, there is provided a method of transmitting digital data, which comprises the steps of causing luminance signal information data and chrominance signal information data which constitute a digital video signal to be subjected to bit-dividing to produce first, second and third divided bit word sequence data, causing each of the first divided bit word sequence data, the second divided bit word sequence data and compound bit word sequence data obtained by adding predetermined bit word data to the third divided bit word sequence data to be subjected to 8B/10B conversion to produce first, second and third 10-bit word sequence data, obtaining first,second and third 8-bit word sequence data based on the first, second and third 10-bit word sequence data, respectively, inserting an additional word data group including 8-bit word synchronous data allotted a predetermined specific code into each of the first, second and third 8-bit word sequence data at predetermined word intervals to produce first, second and third composite 8-bit word sequence data, converting the first, second and third composite 8-bit word sequence data into first, second and third serial data, respectively, and transmitting the first, second and third serial data through first, second and third transmission lines.
According to a fourth aspect of the present invention, there is provided an apparatus for transmitting digital data, which comprises first 8-bit word sequence data producing means for obtaining first 8-bit word sequence data based on first digital image information data, second 8-bit word sequence data producing means for obtaining second 8-bit word sequence data based on second digital image information data, first 8B/10B converting means for causing the first 8-bit word sequence data to be subjected to 8B/10B conversion to produce first 10-bit word sequence data, second 8B/10B converting means for causing the second 8-bit word sequence data to be subjected to 8B/10B conversion to produce second 10-bit word sequence data, first composite data producing means for obtaining third 8-bit word sequence data based on the first 10-bit word sequence data and inserting an additional word data group including 8-bit word synchronous data allotted a predetermined specific code into the third 8-bit word sequence data at predetermined word intervals to produce first composite 8-bit word sequence data, second composite data producing means for obtaining fourth 8-bit word sequence data based on the second 10-bit word sequence data and inserting an additional word data group including 8-bit word synchronous data allotted a predetermined specific code into the fourth 8-bit word sequence data at predetermined word intervals to produce second composite 8-bit word sequence data, and data transmitting means for converting the first and second composite 8-bit word sequence data into first and second serial data, respectively, and transmitting the first and second serial data through first and second transmission lines.
The apparatus according to the fourth aspect of the present invention is used for putting the method according to the first aspect of the present invention into practice.
According to a fifth aspect of the present invention, there is provided an apparatus for transmitting digital data, which comprises bit dividing means for causing luminance signal information data and chrominance signal information data which constitute a digital video signal to be subjected to bit-dividing to produce first and second divided bit word sequence data, first 8B/10B converting means for causing the first divided bit word sequence data to be subjected to 8B/10B conversion to produce first 10-bit word sequence data, second 8B/10B converting means for causing the second divided bit word sequence data or compound bit word sequence data obtained by adding predetermined bit word data to the second divided bit word sequence data to be subjected to 8B/10B conversion to produce second 10-bit word sequence data, first composite data producing means for obtaining first 8-bit word sequence data based on the first 10-bit word sequence data and inserting an additional word data group including 8-bit word synchronous data allotted a predetermined specific code into the first 8-bit word sequence data at predetermined word intervals to produce first composite 8-bit word sequence data, second composite data producing means for obtaining second 8-bit word sequence data based on the second 10-bit word sequence data and inserting an additional word data group including 8-bit word synchronous data allotted a predetermined specific code into the second 8-bit word sequence data at predetermined word intervals to produce second composite 8-bit word sequence data, and data transmitting means for converting the first and second composite 8-bit word sequence data into first and second serial data, respectively, and transmitting the first and second serial data through first and second transmission lines.
The apparatus according to the fifth aspect of the present invention is used for putting the method according to the second aspect of the present invention into practice.
According to a sixth aspect of the present invention, there is provided an apparatus for transmitting digital data, which comprises bit dividing means for causing luminance signal information data and chrominance signal information data which constitute a digital video signal to be subjected to bit-dividing to produce first, second and third divided bit word sequence data, first 8B/10B converting means for causing the first divided bit word sequence data to be subjected to 8B/10B conversion to produce first 10-bit word sequence data, second 8B/10B converting means for causing the second divided bit word sequence data to be subjected to 8B/10B conversion to produce second 10-bit word sequence data, third 8B/10B converting means for causing the third divided bit word sequence data or compound bit word sequence data obtained by adding predetermined bit word data to the third divided bit word sequence data to be subjected to 8B/10B conversion to produce third 10-bit word sequence data, first composite data producing means for obtaining first 8-bit word sequence data based on the first 10-bit word sequence data and inserting an additional word data group including 8-bit word synchronous data allotted a predetermined specific code into the first 8-bit word sequence data at predetermined word intervals to produce first composite 8-bit word sequence data, second composite data producing means for obtaining second 8-bit word sequence data based on the second 10-bit word sequence data and inserting an additional word data group including 8-bit word synchronous data allotted a predetermined specific code into the second 8-bit word sequence data at predetermined word intervals to produce second composite 8-bit word sequence data, third composite data producing means for obtaining second 8-bit word sequence data based on the third 10-bit word sequence data and inserting an additional word data group including 8-bit word synchronous data allotted a predetermined specific code into the third 8-bit word sequence data at predetermined word intervals to produce third composite 8-bit word sequence data, and data transmitting means for converting the first, second and third composite 8-bit word sequence data into first, second and third serial data, respectively, and transmitting the first, second and third serial data through first, second and third transmission lines.
The apparatus according to the sixth aspect of the present invention is used for putting the method according to the third aspect of the present invention into practice.
With the method of or apparatus for transmitting digital data thus constituted in accordance with one of the first to sixth aspects of the present invention, multiplex digital data formed with digital data divided into a plurality of channels for representing the digital video signal can be transmitted in such a manner that 8-bit word sequence data to which word synchronous data each allotted a predetermined specific code are added, are produced based on the digital video signal which are to be transmitted and the 8-bit word sequence data thus produced are transmitted through the data transmission line.